// Wild Magic Source Code
// David Eberly
// http://www.geometrictools.com
// Copyright (c) 1998-2007
//
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation; either version 2.1 of the License, or (at
// your option) any later version.  The license is available for reading at
// either of the locations:
//     http://www.gnu.org/copyleft/lgpl.html
//     http://www.geometrictools.com/License/WildMagicLicense.pdf
// The license applies to versions 0 through 4 of Wild Magic.
//
// Version: 4.0.2 (2006/07/25)

#include "Wm4FoundationPCH.h"
#include "Wm4IntrTriangle3Triangle3.h"
#include "Wm4Intersector1.h"
#include "Wm4IntrTriangle2Triangle2.h"
#include "Wm4Query2.h"

namespace Wm4
{
//----------------------------------------------------------------------------
template <class Real>
IntrTriangle3Triangle3<Real>::IntrTriangle3Triangle3 (
    const Triangle3<Real>& rkTriangle0, const Triangle3<Real>& rkTriangle1)
    :
    m_rkTriangle0(rkTriangle0),
    m_rkTriangle1(rkTriangle1)
{
    ReportCoplanarIntersections = true;
    m_iQuantity = 0;
}
//----------------------------------------------------------------------------
template <class Real>
const Triangle3<Real>& IntrTriangle3Triangle3<Real>::GetTriangle0 () const
{
    return m_rkTriangle0;
}
//----------------------------------------------------------------------------
template <class Real>
const Triangle3<Real>& IntrTriangle3Triangle3<Real>::GetTriangle1 () const
{
    return m_rkTriangle1;
}
//----------------------------------------------------------------------------
template <class Real>
bool IntrTriangle3Triangle3<Real>::Test ()
{
    // get edge vectors for triangle0
    Vector3<Real> akE0[3] =
    {
        m_rkTriangle0.V[1] - m_rkTriangle0.V[0],
        m_rkTriangle0.V[2] - m_rkTriangle0.V[1],
        m_rkTriangle0.V[0] - m_rkTriangle0.V[2]
    };

    // get normal vector of triangle0
    Vector3<Real> kN0 = akE0[0].UnitCross(akE0[1]);

    // project triangle1 onto normal line of triangle0, test for separation
    Real fN0dT0V0 = kN0.Dot(m_rkTriangle0.V[0]);
    Real fMin1, fMax1;
    ProjectOntoAxis(m_rkTriangle1,kN0,fMin1,fMax1);
    if (fN0dT0V0 < fMin1 || fN0dT0V0 > fMax1)
    {
        return false;
    }

    // get edge vectors for triangle1
    Vector3<Real> akE1[3] =
    {
        m_rkTriangle1.V[1] - m_rkTriangle1.V[0],
        m_rkTriangle1.V[2] - m_rkTriangle1.V[1],
        m_rkTriangle1.V[0] - m_rkTriangle1.V[2]
    };

    // get normal vector of triangle1
    Vector3<Real> kN1 = akE1[0].UnitCross(akE1[1]);

    Vector3<Real> kDir;
    Real fMin0, fMax0;
    int i0, i1;

    Vector3<Real> kN0xN1 = kN0.UnitCross(kN1);
    if (kN0xN1.Dot(kN0xN1) >= Math<Real>::ZERO_TOLERANCE)
    {
        // triangles are not parallel

        // Project triangle0 onto normal line of triangle1, test for
        // separation.
        Real fN1dT1V0 = kN1.Dot(m_rkTriangle1.V[0]);
        ProjectOntoAxis(m_rkTriangle0,kN1,fMin0,fMax0);
        if (fN1dT1V0 < fMin0 || fN1dT1V0 > fMax0)
        {
            return false;
        }

        // directions E0[i0]xE1[i1]
        for (i1 = 0; i1 < 3; i1++)
        {
            for (i0 = 0; i0 < 3; i0++)
            {
                kDir = akE0[i0].UnitCross(akE1[i1]);
                ProjectOntoAxis(m_rkTriangle0,kDir,fMin0,fMax0);
                ProjectOntoAxis(m_rkTriangle1,kDir,fMin1,fMax1);
                if (fMax0 < fMin1 || fMax1 < fMin0)
                {
                    return false;
                }
            }
        }
    }
    else  // triangles are parallel (and, in fact, coplanar)
    {
        // directions N0xE0[i0]
        for (i0 = 0; i0 < 3; i0++)
        {
            kDir = kN0.UnitCross(akE0[i0]);
            ProjectOntoAxis(m_rkTriangle0,kDir,fMin0,fMax0);
            ProjectOntoAxis(m_rkTriangle1,kDir,fMin1,fMax1);
            if (fMax0 < fMin1 || fMax1 < fMin0)
            {
                return false;
            }
        }

        // directions N1xE1[i1]
        for (i1 = 0; i1 < 3; i1++)
        {
            kDir = kN1.UnitCross(akE1[i1]);
            ProjectOntoAxis(m_rkTriangle0,kDir,fMin0,fMax0);
            ProjectOntoAxis(m_rkTriangle1,kDir,fMin1,fMax1);
            if (fMax0 < fMin1 || fMax1 < fMin0)
            {
                return false;
            }
        }
    }

    return true;
}
//----------------------------------------------------------------------------
template <class Real>
bool IntrTriangle3Triangle3<Real>::Find ()
{
    int i, iM, iP;

    // Get the plane of triangle0.
    Plane3<Real> kPlane0(m_rkTriangle0.V[0],m_rkTriangle0.V[1],
        m_rkTriangle0.V[2]);

    // Compute the signed distances of triangle1 vertices to plane0.  Use
    // an epsilon-thick plane test.
    int iPos1, iNeg1, iZero1, aiSign1[3];
    Real afDist1[3];
    TrianglePlaneRelations(m_rkTriangle1,kPlane0,afDist1,aiSign1,iPos1,iNeg1,
        iZero1);

    if (iPos1 == 3 || iNeg1 == 3)
    {
        // Triangle1 is fully on one side of plane0.
        return false;
    }

    if (iZero1 == 3)
    {
        // Triangle1 is contained by plane0.
        if (ReportCoplanarIntersections)
        {
            return GetCoplanarIntersection(kPlane0,m_rkTriangle0,
                m_rkTriangle1);
        }
        return false;
    }

    // Check for grazing contact between triangle1 and plane0.
    if (iPos1 == 0 || iNeg1 == 0)
    {
        if (iZero1 == 2)
        {
            // An edge of triangle1 is in plane0.
            for (i = 0; i < 3; i++)
            {
                if (aiSign1[i] != 0)
                {
                    iM = (i + 2) % 3;
                    iP = (i + 1) % 3;
                    return IntersectsSegment(m_rkTriangle0,
                        m_rkTriangle1.V[iM],m_rkTriangle1.V[iP]);
                }
            }
        }
        else // iZero1 == 1
        {
            // A vertex of triangle1 is in plane0.
            for (i = 0; i < 3; i++)
            {
                if (aiSign1[i] == 0)
                {
                    return ContainsPoint(m_rkTriangle0,kPlane0,
                        m_rkTriangle1.V[i]);
                }
            }
        }
    }

    // At this point, triangle1 tranversely intersects plane 0.  Compute the
    // line segment of intersection.  Then test for intersection between this
    // segment and triangle 0.
    Real fT;
    Vector3<Real> kIntr0, kIntr1;
    if (iZero1 == 0)
    {
        int iSign = (iPos1 == 1 ? +1 : -1);
        for (i = 0; i < 3; i++)
        {
            if (aiSign1[i] == iSign)
            {
                iM = (i + 2) % 3;
                iP = (i + 1) % 3;
                fT = afDist1[i]/(afDist1[i] - afDist1[iM]);
                kIntr0 = m_rkTriangle1.V[i] + fT*(m_rkTriangle1.V[iM] -
                    m_rkTriangle1.V[i]);
                fT = afDist1[i]/(afDist1[i] - afDist1[iP]);
                kIntr1 = m_rkTriangle1.V[i] + fT*(m_rkTriangle1.V[iP] -
                    m_rkTriangle1.V[i]);
                return IntersectsSegment(m_rkTriangle0,kIntr0,kIntr1);
            }
        }
    }

    // iZero1 == 1
    for (i = 0; i < 3; i++)
    {
        if (aiSign1[i] == 0)
        {
            iM = (i + 2) % 3;
            iP = (i + 1) % 3;
            fT = afDist1[iM]/(afDist1[iM] - afDist1[iP]);
            kIntr0 = m_rkTriangle1.V[iM] + fT*(m_rkTriangle1.V[iP] -
                m_rkTriangle1.V[iM]);
            return IntersectsSegment(m_rkTriangle0,m_rkTriangle1.V[i],kIntr0);
        }
    }

    assert(false);
    return false;
}
//----------------------------------------------------------------------------
template <class Real>
bool IntrTriangle3Triangle3<Real>::Test (Real fTMax,
    const Vector3<Real>& rkVelocity0, const Vector3<Real>& rkVelocity1)
{
    Real fTFirst = (Real)0.0;
    Real fTLast = Math<Real>::MAX_REAL;

    // velocity relative to triangle0
    Vector3<Real> kVel = rkVelocity1 - rkVelocity0;

    // compute edge and normal directions for triangle0
    Vector3<Real> akE[3] =
    {
        m_rkTriangle0.V[1] - m_rkTriangle0.V[0],
        m_rkTriangle0.V[2] - m_rkTriangle0.V[1],
        m_rkTriangle0.V[0] - m_rkTriangle0.V[2]
    };
    Vector3<Real> kN = akE[0].UnitCross(akE[1]);
    if (!TestOverlap(kN,fTMax,kVel,fTFirst,fTLast))
    {
        return false;
    }

    // compute edge and normal directions for triangle1
    Vector3<Real> akF[3] =
    {
        m_rkTriangle1.V[1] - m_rkTriangle1.V[0],
        m_rkTriangle1.V[2] - m_rkTriangle1.V[1],
        m_rkTriangle1.V[0] - m_rkTriangle1.V[2]
    };
    Vector3<Real> kM = akF[0].UnitCross(akF[1]);

    Vector3<Real> kDir;
    int i0, i1;

    if (Math<Real>::FAbs(kN.Dot(kM)) < 1.0f - Math<Real>::ZERO_TOLERANCE)
    {
        // triangles are not parallel

        // direction M
        if (!TestOverlap(kM,fTMax,kVel,fTFirst,fTLast))
        {
            return false;
        }

        // directions E[i0]xF[i1]
        for (i1 = 0; i1 < 3; i1++)
        {
            for (i0 = 0; i0 < 3; i0++)
            {
                kDir = akE[i0].UnitCross(akF[i1]);
                if (!TestOverlap(kDir,fTMax,kVel,fTFirst,fTLast))
                {
                    return false;
                }
            }
        }
    }
    else  // triangles are parallel (and, in fact, coplanar)
    {
        // directions NxE[i0]
        for (i0 = 0; i0 < 3; i0++)
        {
            kDir = kN.UnitCross(akE[i0]);
            if (!TestOverlap(kDir,fTMax,kVel,fTFirst,fTLast))
            {
                return false;
            }
        }

        // directions NxF[i1]
        for (i1 = 0; i1 < 3; i1++)
        {
            kDir = kM.UnitCross(akF[i1]);
            if (!TestOverlap(kDir,fTMax,kVel,fTFirst,fTLast))
            {
                return false;
            }
        }
    }

    m_fContactTime = fTFirst;
    return true;
}
//----------------------------------------------------------------------------
template <class Real>
bool IntrTriangle3Triangle3<Real>::Find (Real fTMax,
    const Vector3<Real>& rkVelocity0, const Vector3<Real>& rkVelocity1)
{
    Real fTFirst = (Real)0.0;
    Real fTLast = Math<Real>::MAX_REAL;

    // velocity relative to triangle0
    Vector3<Real> kVel = rkVelocity1 - rkVelocity0;

    ContactSide eSide = CS_NONE;
    Configuration kTCfg0, kTCfg1;

    // compute edge and normal directions for triangle0
    Vector3<Real> akE[3] =
    {
        m_rkTriangle0.V[1] - m_rkTriangle0.V[0],
        m_rkTriangle0.V[2] - m_rkTriangle0.V[1],
        m_rkTriangle0.V[0] - m_rkTriangle0.V[2]
    };
    Vector3<Real> kN = akE[0].UnitCross(akE[1]);
    if (!FindOverlap(kN,fTMax,kVel,eSide,kTCfg0,kTCfg1,fTFirst,fTLast))
    {
        return false;
    }

    // compute edge and normal directions for triangle1
    Vector3<Real> akF[3] =
    {
        m_rkTriangle1.V[1] - m_rkTriangle1.V[0],
        m_rkTriangle1.V[2] - m_rkTriangle1.V[1],
        m_rkTriangle1.V[0] - m_rkTriangle1.V[2]
    };
    Vector3<Real> kM = akF[0].UnitCross(akF[1]);

    Vector3<Real> kDir;
    int i0, i1;

    if (Math<Real>::FAbs(kN.Dot(kM)) < 1.0f - Math<Real>::ZERO_TOLERANCE)
    {
        // triangles are not parallel

        // direction M
        if (!FindOverlap(kM,fTMax,kVel,eSide,kTCfg0,kTCfg1,fTFirst,fTLast))
        {
            return false;
        }

        // directions E[i0]xF[i1]
        for (i1 = 0; i1 < 3; i1++)
        {
            for (i0 = 0; i0 < 3; i0++)
            {
                kDir = akE[i0].UnitCross(akF[i1]);
                if (!FindOverlap(kDir,fTMax,kVel,eSide,kTCfg0,kTCfg1,fTFirst,
                    fTLast))
                {
                    return false;
                }
            }
        }
    }
    else  // triangles are parallel (and, in fact, coplanar)
    {
        // directions NxE[i0]
        for (i0 = 0; i0 < 3; i0++)
        {
            kDir = kN.UnitCross(akE[i0]);
            if (!FindOverlap(kDir,fTMax,kVel,eSide,kTCfg0,kTCfg1,fTFirst,
                fTLast))
            {
                return false;
            }
        }

        // directions NxF[i1]
        for (i1 = 0; i1 < 3; i1++)
        {
            kDir = kM.UnitCross(akF[i1]);
            if (!FindOverlap(kDir,fTMax,kVel,eSide,kTCfg0,kTCfg1,fTFirst,
                fTLast))
            {
                return false;
            }
        }
    }
    
    if (fTFirst <= (Real)0.0)
    {
        return false;
    }

    m_fContactTime = fTFirst;

    // adjust U and V for first time of contact before finding contact set
    Triangle3<Real> akMTri0, akMTri1;
    for (i0 = 0; i0 < 3; i0++)
    {
        akMTri0.V[i0] = m_rkTriangle0.V[i0] + fTFirst*rkVelocity0;
        akMTri1.V[i0] = m_rkTriangle1.V[i0] + fTFirst*rkVelocity1;
    }

    FindContactSet(akMTri0,akMTri1,eSide,kTCfg0,kTCfg1);
    return true;
}
//----------------------------------------------------------------------------
template <class Real>
int IntrTriangle3Triangle3<Real>::GetQuantity () const
{
    return m_iQuantity;
}
//----------------------------------------------------------------------------
template <class Real>
const Vector3<Real>& IntrTriangle3Triangle3<Real>::GetPoint (int i) const
{
    assert(0 <= i && i < m_iQuantity);
    return m_akPoint[i];
}
//----------------------------------------------------------------------------
template <class Real>
void IntrTriangle3Triangle3<Real>::ProjectOntoAxis (
    const Triangle3<Real>& rkTri, const Vector3<Real>& rkAxis, Real& rfMin,
    Real& rfMax)
{
    Real fDot0 = rkAxis.Dot(rkTri.V[0]);
    Real fDot1 = rkAxis.Dot(rkTri.V[1]);
    Real fDot2 = rkAxis.Dot(rkTri.V[2]);

    rfMin = fDot0;
    rfMax = rfMin;

    if (fDot1 < rfMin)
    {
        rfMin = fDot1;
    }
    else if (fDot1 > rfMax)
    {
        rfMax = fDot1;
    }

    if (fDot2 < rfMin)
    {
        rfMin = fDot2;
    }
    else if (fDot2 > rfMax)
    {
        rfMax = fDot2;
    }
}
//----------------------------------------------------------------------------
template <class Real>
void IntrTriangle3Triangle3<Real>::TrianglePlaneRelations (
    const Triangle3<Real>& rkTriangle, const Plane3<Real>& rkPlane,
    Real afDistance[3], int aiSign[3], int& riPositive, int& riNegative,
    int& riZero)
{
    // Compute the signed distances of triangle vertices to the plane.  Use
    // an epsilon-thick plane test.
    riPositive = 0;
    riNegative = 0;
    riZero = 0;
    for (int i = 0; i < 3; i++)
    {
        afDistance[i] = rkPlane.DistanceTo(rkTriangle.V[i]);
        if (afDistance[i] > Math<Real>::ZERO_TOLERANCE)
        {
            aiSign[i] = 1;
            riPositive++;
        }
        else if (afDistance[i] < -Math<Real>::ZERO_TOLERANCE)
        {
            aiSign[i] = -1;
            riNegative++;
        }
        else
        {
            afDistance[i] = (Real)0.0;
            aiSign[i] = 0;
            riZero++;
        }
    }
}
//----------------------------------------------------------------------------
template <class Real>
void IntrTriangle3Triangle3<Real>::GetInterval (
    const Triangle3<Real>& rkTriangle, const Line3<Real>& rkLine,
    const Real afDistance[3], const int aiSign[3], Real afParam[2])
{
    // project triangle onto line
    Real afProj[3];
    int i;
    for (i = 0; i < 3; i++)
    {
        Vector3<Real> kDiff = rkTriangle.V[i] - rkLine.Origin;
        afProj[i] = rkLine.Direction.Dot(kDiff);
    }

    // compute transverse intersections of triangle edges with line
    Real fNumer, fDenom;
    int i0, i1, i2;
    int iQuantity = 0;
    for (i0 = 2, i1 = 0; i1 < 3; i0 = i1++)
    {
        if (aiSign[i0]*aiSign[i1] < 0)
        {
            assert( iQuantity < 2 );
            fNumer = afDistance[i0]*afProj[i1] - afDistance[i1]*afProj[i0];
            fDenom = afDistance[i0] - afDistance[i1];
            afParam[iQuantity++] = fNumer/fDenom;
        }
    }

    // check for grazing contact
    if (iQuantity < 2)
    {
        for (i0 = 1, i1 = 2, i2 = 0; i2 < 3; i0 = i1, i1 = i2, i2++)
        {
            if (aiSign[i2] == 0)
            {
                assert(iQuantity < 2);
                afParam[iQuantity++] = afProj[i2];
            }
        }
    }

    // sort
    assert(iQuantity == 1 || iQuantity == 2);
    if (iQuantity == 2)
    {
        if (afParam[0] > afParam[1])
        {
            Real fSave = afParam[0];
            afParam[0] = afParam[1];
            afParam[1] = fSave;
        }
    }
    else
    {
        afParam[1] = afParam[0];
    }
}
//----------------------------------------------------------------------------
template <class Real>
bool IntrTriangle3Triangle3<Real>::ContainsPoint (
    const Triangle3<Real>& rkTriangle, const Plane3<Real>& rkPlane,
    const Vector3<Real>& rkPoint)
{
    Vector3<Real> kU0, kU1;
    Vector3<Real>::GenerateComplementBasis(kU0,kU1,rkPlane.Normal);

    Vector3<Real> kPmV0 = rkPoint - rkTriangle.V[0];
    Vector3<Real> kV1mV0 = rkTriangle.V[1] - rkTriangle.V[0];
    Vector3<Real> kV2mV0 = rkTriangle.V[2] - rkTriangle.V[0];

    Vector2<Real> kProjP(kU0.Dot(kPmV0),kU1.Dot(kPmV0));
    Vector2<Real> akProjV[3] =
    {
        Vector2<Real>::ZERO,
        Vector2<Real>(kU0.Dot(kV1mV0),kU1.Dot(kV1mV0)),
        Vector2<Real>(kU0.Dot(kV2mV0),kU1.Dot(kV2mV0))
    };

    return Query2<Real>(3,akProjV).ToTriangle(kProjP,0,1,2) <= 0;
}
//----------------------------------------------------------------------------
template <class Real>
bool IntrTriangle3Triangle3<Real>::IntersectsSegment (
    const Triangle3<Real>& rkTriangle, const Vector3<Real>& rkEnd0,
    const Vector3<Real>& rkEnd1)
{
    // TO DO.
    return false;
}
//----------------------------------------------------------------------------
template <class Real>
bool IntrTriangle3Triangle3<Real>::GetCoplanarIntersection (
    const Plane3<Real>& rkPlane, const Triangle3<Real>& rkTri0,
    const Triangle3<Real>& rkTri1)
{
    // Project triangles onto coordinate plane most aligned with plane
    // normal.
    int iMaxNormal = 0;
    Real fMax = Math<Real>::FAbs(rkPlane.Normal.X());
    Real fAbs = Math<Real>::FAbs(rkPlane.Normal.Y());
    if (fAbs > fMax)
    {
        iMaxNormal = 1;
        fMax = fAbs;
    }
    fAbs = Math<Real>::FAbs(rkPlane.Normal.Z());
    if (fAbs > fMax)
    {
        iMaxNormal = 2;
    }

    Triangle2<Real> kProjTri0, kProjTri1;
    int i;

    if (iMaxNormal == 0)
    {
        // project onto yz-plane
        for (i = 0; i < 3; i++)
        {
            kProjTri0.V[i].X() = m_rkTriangle0.V[i].Y();
            kProjTri0.V[i].Y() = m_rkTriangle0.V[i].Z();
            kProjTri1.V[i].X() = m_rkTriangle1.V[i].Y();
            kProjTri1.V[i].Y() = m_rkTriangle1.V[i].Z();
        }
    }
    else if (iMaxNormal == 1)
    {
        // project onto xz-plane
        for (i = 0; i < 3; i++)
        {
            kProjTri0.V[i].X() = m_rkTriangle0.V[i].X();
            kProjTri0.V[i].Y() = m_rkTriangle0.V[i].Z();
            kProjTri1.V[i].X() = m_rkTriangle1.V[i].X();
            kProjTri1.V[i].Y() = m_rkTriangle1.V[i].Z();
        }
    }
    else
    {
        // project onto xy-plane
        for (i = 0; i < 3; i++)
        {
            kProjTri0.V[i].X() = m_rkTriangle0.V[i].X();
            kProjTri0.V[i].Y() = m_rkTriangle0.V[i].Y();
            kProjTri1.V[i].X() = m_rkTriangle1.V[i].X();
            kProjTri1.V[i].Y() = m_rkTriangle1.V[i].Y();
        }
    }

    // 2D triangle intersection routines require counterclockwise ordering
    Vector2<Real> kSave;
    Vector2<Real> kEdge0 = kProjTri0.V[1] - kProjTri0.V[0];
    Vector2<Real> kEdge1 = kProjTri0.V[2] - kProjTri0.V[0];
    if (kEdge0.DotPerp(kEdge1) < (Real)0.0)
    {
        // triangle is clockwise, reorder it
        kSave = kProjTri0.V[1];
        kProjTri0.V[1] = kProjTri0.V[2];
        kProjTri0.V[2] = kSave;
    }

    kEdge0 = kProjTri1.V[1] - kProjTri1.V[0];
    kEdge1 = kProjTri1.V[2] - kProjTri1.V[0];
    if (kEdge0.DotPerp(kEdge1) < (Real)0.0)
    {
        // triangle is clockwise, reorder it
        kSave = kProjTri1.V[1];
        kProjTri1.V[1] = kProjTri1.V[2];
        kProjTri1.V[2] = kSave;
    }

    IntrTriangle2Triangle2<Real> kIntr(kProjTri0,kProjTri1);
    if (!kIntr.Find())
    {
        return false;
    }

    // map 2D intersections back to the 3D triangle space
    m_iQuantity = kIntr.GetQuantity();
    if (iMaxNormal == 0)
    {
        Real fInvNX = ((Real)1.0)/rkPlane.Normal.X();
        for (i = 0; i < m_iQuantity; i++)
        {
            m_akPoint[i].Y() = kIntr.GetPoint(i).X();
            m_akPoint[i].Z() = kIntr.GetPoint(i).Y();
            m_akPoint[i].X() = fInvNX*(rkPlane.Constant -
                rkPlane.Normal.Y()*m_akPoint[i].Y() -
                rkPlane.Normal.Z()*m_akPoint[i].Z());
        }
    }
    else if (iMaxNormal == 1)
    {
        Real fInvNY = ((Real)1.0)/rkPlane.Normal.Y();
        for (i = 0; i < m_iQuantity; i++)
        {
            m_akPoint[i].X() = kIntr.GetPoint(i).X();
            m_akPoint[i].Z() = kIntr.GetPoint(i).Y();
            m_akPoint[i].Y() = fInvNY*(rkPlane.Constant -
                rkPlane.Normal.X()*m_akPoint[i].X() -
                rkPlane.Normal.Z()*m_akPoint[i].Z());
        }
    }
    else
    {
        Real fInvNZ = ((Real)1.0)/rkPlane.Normal.Z();
        for (i = 0; i < m_iQuantity; i++)
        {
            m_akPoint[i].X() = kIntr.GetPoint(i).X();
            m_akPoint[i].Y() = kIntr.GetPoint(i).Y();
            m_akPoint[i].Z() = fInvNZ*(rkPlane.Constant -
                rkPlane.Normal.X()*m_akPoint[i].X() -
                rkPlane.Normal.Y()*m_akPoint[i].Y());
        }
    }

    return true;
}
//----------------------------------------------------------------------------
template <class Real>
bool IntrTriangle3Triangle3<Real>::TestOverlap (const Vector3<Real>& rkAxis,
    Real fTMax, Real fSpeed, Real fUMin, Real fUMax, Real fVMin, Real fVMax,
    Real& rfTFirst, Real& rfTLast)
{
    // Constant velocity separating axis test.

    Real fT;

    if (fVMax < fUMin) // V on left of U
    {
        if (fSpeed <= (Real)0.0) // V moving away from U
        {
            return false;
        }

        // find first time of contact on this axis
        fT = (fUMin - fVMax)/fSpeed;
        if (fT > rfTFirst)
        {
            rfTFirst = fT;
        }

        // quick out: intersection after desired time interval
        if (rfTFirst > fTMax)
        {
            return false;   
        }

        // find last time of contact on this axis
        fT = (fUMax - fVMin)/fSpeed;
        if (fT < rfTLast)
        {
            rfTLast = fT;
        }

        // quick out: intersection before desired time interval
        if (rfTFirst > rfTLast)
        {
            return false; 
        }
    }
    else if ( fUMax < fVMin )   // V on right of U
    {
        if (fSpeed >= (Real)0.0) // V moving away from U
        {
            return false;
        }

        // find first time of contact on this axis
        fT = (fUMax - fVMin)/fSpeed;
        if (fT > rfTFirst)
        {
            rfTFirst = fT;
        }

        // quick out: intersection after desired time interval
        if (rfTFirst > fTMax)
        {
            return false;   
        }

        // find last time of contact on this axis
        fT = (fUMin - fVMax)/fSpeed;
        if (fT < rfTLast)
        {
            rfTLast = fT;
        }

        // quick out: intersection before desired time interval
        if (rfTFirst > rfTLast)
        {
            return false; 
        }

    }
    else // V and U on overlapping interval
    {
        if (fSpeed > (Real)0.0)
        {
            // find last time of contact on this axis
            fT = (fUMax - fVMin)/fSpeed;
            if (fT < rfTLast)
            {
                rfTLast = fT;
            }

            // quick out: intersection before desired interval
            if (rfTFirst > rfTLast)
            {
                return false; 
            }
        }
        else if (fSpeed < (Real)0.0)
        {
            // find last time of contact on this axis
            fT = (fUMin - fVMax)/fSpeed;
            if (fT < rfTLast)
            {
                rfTLast = fT;
            }

            // quick out: intersection before desired interval
            if (rfTFirst > rfTLast)
            {
                return false;
            }
        }
    }
    return true;
}
//----------------------------------------------------------------------------
template <class Real>
bool IntrTriangle3Triangle3<Real>::FindOverlap (const Vector3<Real>& rkAxis,
    Real fTMax, Real fSpeed, const Configuration& rkUC, 
    const Configuration& rkVC, ContactSide& rkSide, Configuration& rkTUC,
    Configuration& rkTVC, Real& rfTFirst, Real& rfTLast)
{
    // Constant velocity separating axis test.  UC and VC are the new
    // potential configurations, and TUC and TVC are the best known
    // configurations.

    Real fT;

    if (rkVC.Max < rkUC.Min) // V on left of U
    {
        if (fSpeed <= (Real)0.0) // V moving away from U
        {
            return false;
        }

        // find first time of contact on this axis
        fT = (rkUC.Min - rkVC.Max)/fSpeed;

        // If this is the new maximum first time of contact, set side and
        // configuration.
        if (fT > rfTFirst)
        {
            rfTFirst = fT;
            rkSide = CS_LEFT;
            rkTUC = rkUC;
            rkTVC = rkVC;
        }

        // quick out: intersection after desired interval
        if (rfTFirst > fTMax)
        {
            return false;
        }

        // find last time of contact on this axis
        fT = (rkUC.Max - rkVC.Min)/fSpeed;
        if (fT < rfTLast)
        {
            rfTLast = fT;
        }

        // quick out: intersection before desired interval
        if (rfTFirst > rfTLast)
        {
            return false;
        }
    }
    else if (rkUC.Max < rkVC.Min)   // V on right of U
    {
        if (fSpeed >= (Real)0.0) // V moving away from U
        {
            return false;
        }

        // find first time of contact on this axis
        fT = (rkUC.Max - rkVC.Min)/fSpeed;

        // If this is the new maximum first time of contact, set side and
        // configuration.
        if (fT > rfTFirst)
        {
            rfTFirst = fT;
            rkSide = CS_RIGHT;
            rkTUC = rkUC;
            rkTVC = rkVC;
        }

        // quick out: intersection after desired interval
        if (rfTFirst > fTMax)
        {
            return false;   
        }

        // find last time of contact on this axis
        fT = (rkUC.Min - rkVC.Max)/fSpeed;
        if (fT < rfTLast)
        {
            rfTLast = fT;
        }

        // quick out: intersection before desired interval
        if (rfTFirst > rfTLast)
        {
            return false;
        }
    }
    else // V and U on overlapping interval
    {
        if (fSpeed > (Real)0.0)
        {
            // find last time of contact on this axis
            fT = (rkUC.Max - rkVC.Min)/fSpeed;
            if (fT < rfTLast)
            {
                rfTLast = fT;
            }

            // quick out: intersection before desired interval
            if (rfTFirst > rfTLast)
            {
                return false;
            }
        }
        else if ( fSpeed < (Real)0.0 )
        {
            // find last time of contact on this axis
            fT = (rkUC.Min - rkVC.Max)/fSpeed;
            if (fT < rfTLast)
            {
                rfTLast = fT;
            }

            // quick out: intersection before desired interval
            if (rfTFirst > rfTLast)
            {
                return false;
            }
        }
    }
    return true;
}
//----------------------------------------------------------------------------
template <class Real>
bool IntrTriangle3Triangle3<Real>::TestOverlap (const Vector3<Real>& rkAxis,
    Real fTMax, const Vector3<Real>& rkVelocity, Real& rfTFirst,
    Real& rfTLast)
{
    Real fMin0, fMax0, fMin1, fMax1;
    ProjectOntoAxis(m_rkTriangle0,rkAxis,fMin0,fMax0);
    ProjectOntoAxis(m_rkTriangle1,rkAxis,fMin1,fMax1);
    Real fSpeed = rkVelocity.Dot(rkAxis);
    return TestOverlap(rkAxis,fTMax,fSpeed,fMin0,fMax0,fMin1,fMax1,rfTFirst,
        rfTLast);
}
//----------------------------------------------------------------------------
template <class Real>
bool IntrTriangle3Triangle3<Real>::FindOverlap (const Vector3<Real>& rkAxis,
    Real fTMax, const Vector3<Real>& rkVelocity, ContactSide& reSide,
    Configuration& rkTCfg0, Configuration& rkTCfg1, Real& rfTFirst,
    Real& rfTLast)
{
    Configuration kCfg0, kCfg1;
    ProjectOntoAxis(m_rkTriangle0,rkAxis,kCfg0);
    ProjectOntoAxis(m_rkTriangle1,rkAxis,kCfg1);
    Real fSpeed = rkVelocity.Dot(rkAxis);
    return FindOverlap(rkAxis,fTMax,fSpeed,kCfg0,kCfg1,reSide,rkTCfg0,rkTCfg1,
        rfTFirst,rfTLast);
}
//----------------------------------------------------------------------------
template <class Real>
void IntrTriangle3Triangle3<Real>::ProjectOntoAxis (
    const Triangle3<Real>& rkTri, const Vector3<Real>& rkAxis,
    Configuration& rkCfg)
{
    // find projections of vertices onto potential separating axis
    Real fD0 = rkAxis.Dot(rkTri.V[0]);
    Real fD1 = rkAxis.Dot(rkTri.V[1]);
    Real fD2 = rkAxis.Dot(rkTri.V[2]);

    // explicit sort of vertices to construct a Configuration object
    if (fD0 <= fD1)
    {
        if (fD1 <= fD2) // D0 <= D1 <= D2
        {
            if (fD0 != fD1)
            {
                if (fD1 != fD2)
                {
                    rkCfg.Map = M111;
                }
                else
                {
                    rkCfg.Map = M12;
                }
            }
            else // ( D0 == D1 )
            {
                if (fD1 != fD2)
                {
                    rkCfg.Map = M21;
                }
                else
                {
                    rkCfg.Map = M3;
                }
            }
            rkCfg.Index[0] = 0;
            rkCfg.Index[1] = 1;
            rkCfg.Index[2] = 2;
            rkCfg.Min = fD0;
            rkCfg.Max = fD2;
        }
        else if (fD0 <= fD2) // D0 <= D2 < D1
        {
            if (fD0 != fD2)
            {
                rkCfg.Map = M111;
                rkCfg.Index[0] = 0;
                rkCfg.Index[1] = 2;
                rkCfg.Index[2] = 1;
            }
            else
            {
                rkCfg.Map = M21;
                rkCfg.Index[0] = 2;
                rkCfg.Index[1] = 0;
                rkCfg.Index[2] = 1;
            }
            rkCfg.Min = fD0;
            rkCfg.Max = fD1;
        }
        else // D2 < D0 <= D1
        {
            if (fD0 != fD1)
            {
                rkCfg.Map = M111;
            }
            else
            {
                rkCfg.Map = M12;
            }

            rkCfg.Index[0] = 2;
            rkCfg.Index[1] = 0;
            rkCfg.Index[2] = 1;
            rkCfg.Min = fD2;
            rkCfg.Max = fD1;
        }
    }
    else if (fD2 <= fD1) // D2 <= D1 < D0
    {
        if (fD2 != fD1)
        {
            rkCfg.Map = M111;
            rkCfg.Index[0] = 2;
            rkCfg.Index[1] = 1;
            rkCfg.Index[2] = 0;
        }
        else
        {
            rkCfg.Map = M21;
            rkCfg.Index[0] = 1;
            rkCfg.Index[1] = 2;
            rkCfg.Index[2] = 0;

        }
        rkCfg.Min = fD2;
        rkCfg.Max = fD0;
    }
    else if (fD2 <= fD0) // D1 < D2 <= D0
    {
        if (fD2 != fD0) 
        {
            rkCfg.Map = M111;
        }
        else
        {
            rkCfg.Map = M12;
        }

        rkCfg.Index[0] = 1;
        rkCfg.Index[1] = 2;
        rkCfg.Index[2] = 0;
        rkCfg.Min = fD1;
        rkCfg.Max = fD0;
    }
    else // D1 < D0 < D2
    {
        rkCfg.Map = M111;
        rkCfg.Index[0] = 1;
        rkCfg.Index[1] = 0;
        rkCfg.Index[2] = 2;
        rkCfg.Min = fD1;
        rkCfg.Max = fD2;
    }
}
//----------------------------------------------------------------------------
template <class Real>
void IntrTriangle3Triangle3<Real>::FindContactSet (
    const Triangle3<Real>& rkTri0, const Triangle3<Real>& rkTri1,
    ContactSide& reSide, Configuration& rkCfg0, Configuration& rkCfg1)
{
    if (reSide == CS_RIGHT) // tri1 to the right of tri0
    {
        if (rkCfg0.Map == M21 || rkCfg0.Map == M111)
        {
            // tri0 touching tri1 at a single point
            m_iQuantity = 1;
            m_akPoint[0] = rkTri0.V[2];
        }
        else if (rkCfg1.Map == M12 || rkCfg1.Map == M111)
        {
            // tri1 touching tri0 at a single point
            m_iQuantity = 1;
            m_akPoint[0] = rkTri1.V[0];
        }
        else if (rkCfg0.Map == M12)
        {
            if (rkCfg1.Map == M21)
            {
                // edge0-edge1 intersection
                GetEdgeEdgeIntersection(rkTri0.V[1],rkTri0.V[2],rkTri1.V[0],
                    rkTri1.V[1]);
            }
            else // rkCfg1.Map == m3
            {
                // uedge-vface intersection
                //Vector3<Real> akEdge0[2] = { rkTri0.V[1], rkTri0.V[2] };
                //FindContactSetColinearLineTri(akEdge0,rkTri1,riQuantity,
                //    akP);
            }
        }
        else // rkCfg0.Map == M3
        {
            if (rkCfg1.Map == M21)
            {
                // face0-edge1 intersection
                //Vector3<Real> akEdge1[2] = { rkTri1.V[0], rkTri1.V[1] };
                //FindContactSetColinearLineTri(akEdge1,rkTri0,riQuantity,
                //    akP);
            } 
            else // rkCfg1.Map == M3
            {
                // face0-face1 intersection
                Plane3<Real> kPlane0(rkTri0.V[0],rkTri0.V[1],rkTri0.V[2]);
                GetCoplanarIntersection(kPlane0,rkTri0,rkTri1);
            }
        }
    }
    else if (reSide == CS_LEFT) // tri1 to the left of tri0
    {
        if (rkCfg1.Map == M21 || rkCfg1.Map == M111)
        {
            // tri1 touching tri0 at a single point
            m_iQuantity = 1;
            m_akPoint[0] = rkTri1.V[2];
        }
        else if (rkCfg0.Map == M12 || rkCfg0.Map == M111)
        {
            // tri0 touching tri1 at a single point
            m_iQuantity = 1;
            m_akPoint[0] = rkTri0.V[0];
        }
        else if (rkCfg1.Map == M12)
        {
            if (rkCfg0.Map == M21)
            {
                // edge0-edge1 intersection
                GetEdgeEdgeIntersection(rkTri0.V[0],rkTri0.V[1],rkTri1.V[1],
                    rkTri1.V[2]);
            }
            else // rkCfg0.Map == M3
            {
                // edge1-face0 intersection
                //Vector3<Real> akEdge1[2] = { rkTri1.V[1], rkTri1.V[2] };
                //FindContactSetColinearLineTri(akEdge1,rkTri0,riQuantity,
                //    akP);
            }
        }
        else // rkCfg1.Map == M3
        {
            if (rkCfg0.Map == M21)
            {
                // edge0-face1 intersection
                //Vector3<Real> akEdge0[2] = { rkTri0.V[0], rkTri0.V[1] };
                //FindContactSetColinearLineTri(akEdge0,rkTri1,riQuantity,
                //    akP);
            } 
            else // rkCfg0.Map == M
            {
                // face0-face1 intersection
                Plane3<Real> kPlane0(rkTri0.V[0],rkTri0.V[1],rkTri0.V[2]);
                GetCoplanarIntersection(kPlane0,rkTri0,rkTri1);
            }
        }
    }
    else // reSide == CS_NONE
    {
        // triangles are already intersecting tranversely
        IntrTriangle3Triangle3<Real>(rkTri0,rkTri1).Find();
    }
}
//----------------------------------------------------------------------------
template <class Real>
void IntrTriangle3Triangle3<Real>::GetEdgeEdgeIntersection (
    const Vector3<Real>& rkU0, const Vector3<Real>& rkU1,
    const Vector3<Real>& rkV0, const Vector3<Real>& rkV1)
{
    // TO DO.
}
//----------------------------------------------------------------------------

//----------------------------------------------------------------------------
// explicit instantiation
//----------------------------------------------------------------------------
template WM4_FOUNDATION_ITEM
class IntrTriangle3Triangle3<float>;

template WM4_FOUNDATION_ITEM
class IntrTriangle3Triangle3<double>;
//----------------------------------------------------------------------------
}
